There’s nothing subtle about the Miata-based Speedster and Spyder concepts Mazda built for the 2015 SEMA show. The Speedster is a grab-the-Sawzall-and-cut-your-way-to-lightness exercise that would make a gastric-bypass surgeon proud. The Spyder, for its part, achieves exotic status by flaunting its own impracticality. ­Neither car has side windows, and neither is an original idea; the previous-generation MX-5 spawned similar concepts, the Superlight at Frankfurt in 2009 and another Spyder at SEMA in 2011. Yet because they are Miatas and we are red-blooded auto enthusiasts, we cannot look away.

Exterior

The Speedster quite obviously tips its hat to those racing machines from the era in which men actually wore hats. Gone are the A-pillars, windshield, and convertible top, supplanted by a carbon-fiber front deflector and a hard tonneau cover under which two helmets can be stored. Also excised in the name of lightness: the infotainment screen and audio system, including the speakers. Lighter components replace the stock seats and inner door ­panels for a total savings of about 250 pounds, according to Mazda.

The Spyder swaps the factory folding roof for a bikini top developed by ASC. While it might look like a simple piece of canvas, there’s actually a rigid panel sewn into it. The top uses the factory latching system at the windshield header, with further attachments inside the trunk. Closing the trunklid tensions the buttresses and secures the whole assembly. Unfortunately, this prototype top does not fit in the trunk, at least not yet.

Racing Beat developed the center-exit exhaust; Mazda designed the tips.

PAUL BARSHON, THE MANUFACTURER

Interior

The Speedster’s cabin is tricked out with plenty of suede and leather. Carbon-fiber door panels drop 1.5 pounds from the stock plastic ones, and the leather straps that replace the handles are auto-show porn. Japa­nese seat supplier Delta created a carbon-fiber version of its sporty, highly bolstered Mu-Len seat for the Speedster, dropping the MX-5’s already-low H-point another 1.5 inches. Mazda also relocated the push-button ­ignition to the center of the transmission tunnel, just behind the parking brake, amplifying the Speedster’s race-car vibes.

PAUL BARSHON, THE MANUFACTURER

The Spyder’s interior retains more of its stock appearance than does the Speedster, except for a ­gorgeous application of aniline-dyed leather in a deep chestnut color. It wraps completely around the cockpit, covering the door panels as well as the center of the dashboard. The seats are dressed up in the material as well, with pale-orange inserts to match the abundant stitching. It’s striking and succeeds in elevating the inexpensive Miata’s presentation such that comparisons with Porsche’s Boxster Spyder won’t be limited to their shared nomenclature.

PAUL BARSHON, THE MANUFACTURER

Hardware

Both cars sit 1.2 inches lower than stock, the Speedster by virtue of a K&W adjustable coil-over kit and the Spyder via nonadjustable springs. The exhaust plumbing is by Racing Beat. The aluminum muffler is lighter than the Miata’s and uses stock hangers, though Mazda designed specific center-exit exhaust tips for each of the concepts. The MX-5’s optional Club package donates its aero pieces and Brembo brakes. Wider aftermarket wheels and tires unique to each concept complete the modest performance upgrades.

Left: Since it lacks a windshield, the Speedster has cubbies for two helmets behind the seats.

PAUL BARSHON, THE MANUFACTURER

Prospects

Ken Saward, Mazda’s design manager for the concepts, is adamant that these cars are design studies. Since the fourth-gen MX-5 is still new, he says, Mazda didn’t want to change too much about the car. Though we caught him using the phrase “in production” during our interview, we don’t imagine there’s much chance of ­seeing a factory Speedster. Certainly the Spyder would make a more feasible production car. We’re holding out hope.